SALZBURG, Austria – British composer Thomas Ades blurs the lines between cinema and opera in his edgy new work “The Exterminating Angel” based on director Luis Bunuel’s film of the same name about guests trapped by an invisible force at an upper-crust dinner party.

The opera, which had its premiere at the Salzburg Festival on Thursday (July 28) with Ades, 45, conducting,  includes scenes depicting attempted rape, a double suicide, a stabbing and witchcraft. It also has three live sheep on stage and features an ominous and convincing — if not real — black bear.

With a libretto by the Irish-born Tom Cairns, who also directed, Ades has gone for a wide colour palette of sound. In addition to extensive use of church bells,  the composer for the first time employs the haunting strains of the science-fiction film electronic wave-making instrument the “ondes Martenot” — the sonic voice of the mysterious force that entraps the guests.

The work, which next year goes to the Royal Opera in London and the Metropolitan Opera in New York, was sung by a starry cast, including Swedish mezzo-soprano Anne Sofie von Otter, British bass John Tomlinson,  American soprano Audrey Luna and British baritone Thomas Allen.

The opera, like the film, is set at a post-opera dinner party given by the wealthy couple Edmundo di Nobile (American tenor Charles Workman) and his wife Lucia (South African soprano Amanda Echalaz).

All but one of the servants, sensing something is not right, desert the mansion before the dinner, on any lame pretext, outraging the hostess.

The servants’ premonitions are proven correct when all the guests are still at the party at 5 a.m., and realise they are unable to leave the drawing room, try as they may. Though there is no visible barrier, when they walk to the archway leading to the next room they stop and turn around, or can walk no further.

As food and drink run out, the guests break into a pipe for water while violent and perverse urges surface among them. Crowds gather outside the mansion, but are unable to enter it.

In the third and final act, director Cairns unleashes some spectacular stagecraft. An elderly colonel swoops across the stage like an eagle, alighting on a recumbent woman party guest in an attempt to rape her. Three women who have discovered their inner witch powers shriek that a potion to lift the spell will require “innocent blood”. And a woman so longs for her young son at home that she cradles the carcass of a dead sheep.

Meanwhile a huge black bear appears in the shadows beyond the drawing room, to underscore that there are threatening forces out there, possibly worse than the strange power trapping the dinner guests.

All this and more takes place over two and a half hours to one of Ades’s darkest and most powerful scores. Although there are recognisable tropes from his last opera, “The Tempest”, based on Shakespeare’s play, this time Ades ratchets up the tension to the breaking point — before the guests and the audience are released in a stunning aria sung by Luna, whose voice soars into the highest registers.

In an interview published in the programme notes, Ades says the idea for making an opera version of the Spanish-born Bunuel’s film, which is often interpreted as a criticism of totalitarianism and the powers of the elite, began some 15 years ago. He also recalled having seen the film in his early teens.

Neither the film nor the opera spells out what the “exterminating angel” is, making the mysterious curse that has befallen the dinner guests all the more frightening.

“In a way, the exterminating angel is an absence — an absence of will, of purpose, of action. Why do we ever do anything?,” Ades says.

“The film poses this question in a very pure form, and the answer is: because otherwise we would be at the end, with death and extermination.”

— Michael Roddy